Background: Associations between air pollution exposure and chronic diseases have been well-documented. However, the effects of early-life exposure to fine particulate matter (PM2.5) on adulthood hypertension and their dynamic associations remain unclear. Methods: A total of 4,272 participants with 17,814 medical examinations from 2 ongoing cohorts in Taiwan and Hong were included during the study period from 2000-2018. We used a satellite-based model to assess 2-year average PM2.5 exposure at a resolution of 1 km2. A linear mixed model was used to examine the associations with blood pressure. We used a Cox regression model with time-dependent covariates was used to examine the overall association with the development of hypertension in adulthood. Life-course mixed models were used to examine the health effects of PM2.5 exposure at different life stages. Results: For each 10 g/m3 increase in PM2.5, the overall risk of adulthood hypertension increased by 40% (95% confidence interval [CI]: 8%-80%). The health effects of PM2.5 exposure at different life-stages on incident hypertension were generally independent of each other. In critical model, the risk of hypertension increased 23%, 27% and 55% for each 10 g/m3 increase in PM2.5 exposure during school age, adolescence and adulthood, respectively. Similar associations were found with blood pressure. Higher level of PM2.5 exposure at different life stages was associated with elevated blood pressure and a higher risk of developing hypertension in adulthood. Conclusions: Association between PM2.5 and adulthood hypertension can be traced back to childhood. Our study suggests that life-course control of air pollution exposure should be implemented to alleviate the burden of adult hypertension.